1. Field of the Invention
The present invention relates generally to wall plates for electrical wiring devices, and particularly to wall plates for commercial dimmers.
2. Technical Background
Multi-gang device boxes are configured to accommodate multiple wiring devices side by side. The multi-gang box includes several pairs of mounting tabs, each pair being separated from an adjacent pair of mounting tabs by a standard distance, such as 1.812 inches. This standard distance is commonly referred to as a “single-gang width.” Of course, each pair of mounting tabs includes a fastener aperture disposed in the top wall of the box and a corresponding fastener aperture disposed in the bottom wall of the box. The centerline passing through the top and bottom fastener holes of each pair is substantially parallel to the side walls of the box. Each device mounted in the multi-gang box is fastened to the top and bottom holes by inserting a fastener screw therein. There is typically some play between the wiring device and the mounting holes in the multi-gang junction box so the installer can compensate for a junction box that has not been perfectly aligned during installation. This gives rise to the problem that the wiring devices are not aligned to each other by the box.
The present invention is directed to commercial dimmer wiring devices. A one (1) gang dimmer, of course, is configured to be disposed within a single gang width. As the name suggests, 1½ gang dimmers, 2 gang dimmers and 2½ gang dimmers require a 1½ gang width, a 2 gang width and a 2½ gang width, respectively. The dimmer size relates to the wattage of the load it is related to control. The load current causes a certain amount of heating in the dimmer itself such that the greater the load current, the greater the amount of heating. The heat generated by the dimmer must be dissipated by a heat sink. The heat sink is typically implemented using a thermally conductive plate member that has a surface area greater than the “footprint” of the dimmer itself. It is the heat sink area that typically establishes the size of the dimmer.
The dimmer mounts to the multi-gang box by way of fasteners that pass through holes in the heat sink that are in alignment with mounting tab holes. There are redundant pairs of holes in the top and bottom of the heat sink. This allows the installer to align the box to the closest available pair of mounting tab holes. In some dimmers, the portion of the heat sink overhanging the side of the dimmer is scored. The score lines permit the installer to snap-off and physically remove edge portions of the heat sink. The removable edge portions are often referred to as heat sink “fins.” The fins are removed for a variety of reasons and provide the installer with flexibility. Regardless of whether or not the dimmer includes fins and whether or not the fins have been removed, adjacent dimmers are mounted inside the box edge to edge without wasted box space.
Referring to FIG. 1, after the dimmers 2 are mounted, one or more wall plates 3 must be mounted to the multi-gang box 1 to cover them. In one approach, the installer attempts to install one individual wall plate over each dimmer mounted on the box. The installer then tries to attach the individual wall plates on the box such that they abut each other edge-to-edge. However, the individual dimmers are usually not perfectly aligned with each other. The edges of the heat sinks may be raised relative to each other, the side edges of the heat sink may not be vertically aligned with each other, and the bottom edges of the heat sink may not be in perfect horizontal alignment. Because the individual dimmers are not perfectly aligned with each other in three-dimensional space, the wall plates will not be perfectly aligned either. The wall plates will exhibit a stepped appearance that is both unacceptable and undesirable. The edges of the individual wall plates look rough and non-uniform. This is further exacerbated when dimmers of different width are installed. In this case, certain wall plates may be used that have score lines that allow installers to snap of unwanted portions. At the end of the day, the installer will view the installed wall plates, find them to be grossly out of alignment, remove the wall plates, and start over in an attempt to perfectly align the dimmers. This procedure may be repeated several times before the installer gets it right or gives up.
In another approach that has been considered, designers avoid the use of individual plates by ordering a custom plate to fit over the entire ensemble of dimmers. The drawbacks to this approach are the cost and lead time of having a custom wall plate manufactured. Both of these factors are usually prohibitive.
As can be seen, an alignment issue arises whenever wiring devices of dissimilar width are installed in a multi-gang junction box. Although the problem has been described with respect to commercial dimmers, other voltage controllers such as fan speed controllers, dehummers (a type of fan speed controller), and combination dimmer/fan speed controllers are also germane. The size of a voltage controller may relate to the inclusion of other wiring device features such as switches, receptacles, sensors, or lights. Alternatively, such wiring devices may not be combined with a voltage controller. Instead, they are disposed as separate wiring devices elsewhere in the multi-gang junction box, further increasing the variety of wiring device widths.
What is needed, therefore, is a system that addressees the needs described above. In particular, a modular wall plate system is needed that conveniently gangs dimmers of varying widths together in a multi-gang box in an aesthetically pleasing way.